Lately I have been reading and seeing on T.V. the big concern of gas-ethanol mix and outboards. Apparently the problem seems to be water collecting in the fuel tank and then this is pumped into the engine and possible damage or problems result. I have a 2006 75 H.P. e tec and there is already a water filter that is part of the engine under the cowling. Since I have never run an outboard without a water sediment seperator, and since my dealer seemed to think it was not necessary, I took his advise. However, I am constantly checking the onboard filter and just needed to get reassurance that I do not have to be redundant. I use xd 100.